George's Marvellous Medicine (or "Marvelous" in the US print-runs) is a children's book written by Roald Dahl and illustrated by Quentin Blake.

George Kranky, a small boy who lives on a farm with his mother, father and grandmother, is fed up of his Grandma's selfishness, grumpiness and her attitude towards him. George seeks to cure it by brewing a special medicine to cure her (made from every harmful product in the house, and several animal medicines from his father's shed), only to end up making his Grandma as tall as a house. While this does not improve her disposition, it does make her happier.